1. Field of the Invention
Aspects of the present invention relate to the transmission of wireless power and, more particularly, to an apparatus and method for detecting foreign objects in a wireless power transmission system.
2. Description of the Related Art
In general, a battery pack functions to receive electric power (electrical energy) from an external charger and supply a power source for driving a portable terminal (e.g., a mobile phone or a PDA) in a charging state. The battery pack includes a battery cell for charging the electrical energy, a circuit for charging or discharging the battery cell (i.e., supply the electrical energy to the portable terminal), etc.
An electrical coupling method for coupling the battery pack and the charger for charging the battery pack used in this portable terminal with the electrical energy source includes a terminal supply method for receiving a commercial power source, converting the commercial power source into voltage and current corresponding to the battery pack, and supplying electrical energy to the battery pack through the terminal of the battery pack.
However, the terminal supply method has problems, such as an instant discharge phenomenon due to a potential difference between terminals, damage and the occurrence of a fire due to foreign objects, natural discharge, and a reduction in the lifespan and performance of a battery pack.
In order to solve the problems, contactless type charging systems and control methods using a wireless power transmission method are being recently proposed.
The contactless type charging system includes a contactless power transmission apparatus for supplying electrical energy according to a wireless power transmission method, a contactless power reception apparatus for receiving the electrical energy from the contactless power transmission apparatus, and charging a battery cell with the electrical energy, etc.
Meanwhile, in the contactless type charging system, the contactless power reception apparatus is charged in the state in which it is placed in the contactless power transmission apparatus owing to the characteristics of the contactless method.
Here, if foreign objects, such as metal, are placed in the contactless power transmission apparatus, the transmission of the wireless power is not smoothly performed due to the foreign objects and there is a problem in that a product is damaged due to an overload.